Practice Questions (Organic Chemistry)

1(a) A and B have molecular formula C8H10. When A and B are treated with hot concentrated potassium manganate(VII), A forms C7H6O2 while B forms C8H6O4. B reacts with thionyl chloride, SOCl2 to form C and C reacts with methanol, CH3OH in the presence of a catalyst to form D, C10H10O4. Deduce the formula of A to D. [4]

(b)(i) Draw the structural formulae of three alcohols with the molecular formula C5H12O. Label your structures E, F and G. [3]

(ii) Label the chiral carbons on E to G with an asterisk on each carbon. [2]

(iii) E, F and G are treated with an excess of acidified potassium dichromate(VI). E has no reaction with the reagent while F and G gave different products. Suggest simple chemical tests to identify the functional group on each of the products of F and G. Write chemical equations of all the reactions. [8]

(iv) F is treated with PCl3 then with NaCN. After that, it is treated with LiAlH4 to give H. Draw the structural formula of H. [3]

Answers :

1(a) A is C6H5CH2CH3.
B is (CH3)C6H4(CH3). The two methyl groups on the phenyl ring can be in any positions.
When A and B are treated with KMnO4, A becomes C6H5COOH. B becomes HOOCC6H4COOH. B reacts with thionyl chloride to form C, which is ClOCC6H4COCl. C then reacts with methanol to form a diester, D, CH3OOCC6H4COOCH3.

(b) E is a tertiary alcohol, CH3CH2COH(CH3)2

F could be a primary alcohol, CH3CH2CH2CH2CH2OH

G could be a secondary alcohol, CH3CHOHCH2CH2CH3

(iii) E has no reaction with K2Cr2O7 because tertiary alcohols cannot be oxidised.
F is oxidised to a carboxylic acid, CH3CH2CH2CH2COOH. I can add sodium carbonate to the acid and carbon dioxide that is liberated gives a white precipitate with calcium hydroxide.
G is oxidised to a ketone, CH3COCH2CH2CH3. The ketone gives an orange precipitate with 2,4-DNPH.

(iv) F reacts with PCl3 to form CH3CH2CH2CH2CH2Cl. It then reacts with NaCN to form CH3CH2CH2CH2CH2CN. Then it reacts with LiAlH4, a reducing agent, to form an amine, H, which is CH3CH2CH2CH2CH2CH2NH2.


  1. The one formula that over chemistry teacher describe to us is, the chemistry is level of imagination to read more formulas. chemistry is the home of the formulas and numerical's.

  2. Awesome blog for a level students. They can read this understand it and will review new ideas which is authentic and realistic. Students should try this for the practical based proects and love this blog.

  3. That is great and very informative article about rephrasing which is good for every student who like to study about writing. I really happy to read about that post. Keep sharing such kind of article. visit website and learn many thing.

  4. About the organic chemistry you can learn the better life and can enjoy the new practice questions in this session. Just get the new area and look here if you're interested in order to get the good grades in the exams.

  5. That's excellent and incredibly educational post regarding rephrasing that will work for each and every college student that prefer to research regarding composing. I truly pleased to find out about which publish. Maintain discussing this kind of type of post. Visit here


Post a Comment

Popular posts from this blog

Tips for 2020 JC H2 Chemistry Students

Summary notes of Transition Metals and their compounds